1. Field of the Invention
The present invention relates, generally, to a mobile station for adaptation to a radio interface access method which is supported by a mobile radio telephone network and, more specifically, to a method and communication system for adapting such a mobile station to a radio interface access method wherein known disadvantages relating to limited transmission capacity may be avoided.
2. Description of the Prior Arts
In mobile radiotelephone systems of the third generation such as UMTS (Universal Mobile Telecommunication System), a variety of radio interface technologies probably both be used for radio transmission between base stations of a mobile radiotelephone network and mobile stations. However, different radio interface technologies means different radio interface access methods. In the document xe2x80x9cTdoc SMG2 UMTS 52/97xe2x80x9d (ETSI STC SMG2 UMTS ad hoc of Apr. 8-10, 1997 in Lulea Sweden: pp 1-2), the use of a global pilot channel on a frequency or, respectively, in a frequency spectrum, that is uniform throughout the world is proposed in order to allow a mobile subscriber the possibility of worldwide access to every local mobile radiotelephone network. On this pilot channel, information is transmitted to the mobile stations with the aid of which the mobile stations can adapt to the radio interface access method of a local mobile radiotelephone network. A mobile station that is suitable for this adaptation capability must be multimode capable; that is, all components that are required for the adaptation to the access method are embodied in the mobile station, and the information transmitted on the pilot channel serves merely to switching between the respective components that are used in the access method.
The disadvantage of this method is that a frequency, or a respectively, a frequency spectrum, must be reserved worldwide for the pilot channel. Because radio frequencies are only available to a limited extent, this pilot channel is designed very simple and with a limited transmission capacity in order to be able to use it in all mobile radiotelephone systems. However a low transmission capacity would condition the use of the above-described multimode mobile stations exclusively.
It is taught in xe2x80x9cSoftware Radio Technology Challenges and Opportunities First European Workshop on Software Radiosxe2x80x9d (J. Mitola, Software Radio Workshop, May 29, 1997, Brussels: p 2 and 3) that mobile stations can be adapted to different radio interface technologies by programming modules. For instance, adaptation to a multiplex method (FDMA,TDMA,CDMA or hybrids), to a radio interface (channel coding, error protocols, etc.), or to a modulation method can be accomplished.
The possibility of utilizing mobile stations which implement a radio interface access method using programming modules that can be downloaded from the base stations would be out of the question given the use of the above-described pilot channel, the reason for this is that the transmission capacity would not be sufficient for a transmission of larger programming modules in particular.
GB 2 294 844 teaches a communication system in which several communication systems are connected by means of a central connection system. A list of the available communication systems and their specific characteristics is transmitted to a subscriber station upon request by a shared communication system. When a suitable communication system has been selected by the subscriber station, a corresponding program is sent by the shared communication system. With the aid of this program, the subscriber station then executes a configuration onto the selected communication system.
The present invention is, therefore, directed to each of a method, a mobile station and a communication system that avoids the above-described disadvantages related to the limited transmission capacity of the pilot channel.
Accordingly, the present invention is directed to a mobile station situated in a radio coverage area of a mobile radiotelephone network which generates an adaptation to a radio interface access method that is supported by this mobile radiotelephone network. The method includes the sending of a pilot channel by at least one broadcast transmitting station of a public broadcast system in the radio coverage area of the mobile radiotelephone network and its reception by the mobile station. Signaling information about at least one radio interface access method that is supported by the mobile radiotelephone network is transmitted on the pilot channel.
The mobile station then evaluates this signaling information, selects a radio interface access method, and generates an adaptation to the selected radio interface access method.
In an embodiment of the present invention, the pilot channel is sent together with RDS information, preferably periodically, on at least one radio transmission channel in a frequency spectrum of a public broadcast system in the region of the radio coverage by the mobile radiotelephone network.
In a further embodiment, the pilot channel receiver in the mobile station is designed as an FM receiver with an RDS decoder embodied therein, in order to detect a radio transmission channel that conducts RDS information in the frequency spectrum of the public broadcast system and to receive the pilot channel.
The use of the infrastructure of the public broadcast system has the advantages that the frequency spectrum for public broadcast systems is nearly identical across the world (for instance 87.5-108 Mhz), and that the transmission of the RDS information proceeds according to a standardized method. Furthermore, the worldwide infrastructure of the broadcast systems already in existence, which has a nearly total coverage of the terrestrial regions, as well as the economical FM receiver technology that is available in highly integrated form, contribute to a simple and cost-effective embodiment of the present invention. An integration of the FM receiver technology does not mean a significant rise in the share of costs or a greater complexity of the mobile station.
In another embodiment of the present invention, at least one broadband transmission channel that has a high transmission capacity is indicated with the aid of a pointer which is transmitted on the pilot channel.
At least one programming module for a program-based adaptation of the mobile station to the selected radio interface access method from a programming standpoint is transmitted on the broadband channel, preferably periodically.
Moreover, an adaptation device in the mobile station generates an adaptation of the mobile station to the selected radio service access method using the programming modules.
The broadband transmission channel preferably is sent in a frequency spectrum of a digital broadcast system by at least one digital broadcast transmitting station in the radio coverage area of the mobile radiotelephone network.
A digital broadband receiver in the mobile station that is laid out to the frequency spectrum of the digital broadcast system detects the broadband transmission channel indicated by the pointer and receives the programming modules. This development has the advantage that the technology of the digital broadband receiver, like that of the FM receiver, is available in highly integrated form and at a low price. Furthermore, the digital broadcast system offers nearly worldwide coverage coupled with a high transmission capacity that is far higher than the capacity of a transmission channel of a mobile radiotelephone network.
The beneficial effect of this described embodiment is that the pilot channel with the signaling information can be designed so as to be very narrowband, in order to make global signaling information of the mobile radiotelephone network that is relevant for the selection of the radio interface access method available to the mobile station. Based on this signaling information, a multimode capable mobile station can generate an adaptation to a radio interface access method. A mobile station with the capability of program-based adaptation to a radio interface access method is directed by the pointer to the broadband transmission channel on which the programming modules are sent. This design enables the use of a variety of types of mobile stations.
In a further embodiment of the present invention, the programming modules may, be transmitted on the broadband transmission channel in at least one data packet. In this case, the mobile station can contain a data packet memory in which the received data packets are stored. Given the placement of ahead word or a frame check sum at the front and back of each data packet, respectively, it can be checked in an evaluating device of the mobile station whether all data packets required for the adaptation to the selected radio interface access method have been received. A beneficial effect of this development is that the mobile station can begin to receive the data packets that are periodically transmitted on the broadband transmission channel at any time in order to generate the adaptation to the selected radio interface access method subsequent to complete reception.